I think O'Meara's time has come and gone. He would be 53 in 2010 and the PGA of America likes their captains to be in their mid-to-late 40s. The captain will need to have won at least one major in his career so that eliminates Kenny Perry unless he wins one next year at the age of 49 (doubtful). And the theory of the PGA always taking PGA champions was blown out of the water when Larry Nelson was passed over for Tom Kite in '97. Freddie Couples is waaaay too low key for the Ryder Cup captaincy (but just to show how little the Presidents Cup really matters, Freddie is the U.S. captain in 2009 at Harding Park in San Fran).
So for 2010 that leaves DLIII. He'll be the perfect age (46 in 2010), is still an active tour player and so knows the locker room well, is a past major champion (PGA championship at that), has Ryder Cup experience galore (played in six consecutive Cups from '93 to '04 including two winning teams, one at the Belfry in '93 and of course at Brookline in '99).
After that, the list gets a bit short though. Corey Pavin will be 51 in 2010 and has been absent from Ryder play since 1995. He might get the nod, though, based on his competitiveness. Bob Tway never played in a Ryder Cup so he won't even be in the discussion. David Toms played in three in a row from '02 to '06 and will be 43 in 2010. He might be a good choice but may want to try to compete for a spot on the team on his own.
Down the line, of course, Tiger, Phil, Justin, and Jim Furyk, will all get their shots. But the PGA of America may have to resort to non-major winners at some point because Tiger's dominance and the rise of the Europeans has resulted in fewer and fewer Americans winning majors in the last few years. (disclaimer, I have not researched this statement but in general I think it's true).